This program is directed at increasing our understanding of the regulation of the peripheral circulation. It approaches circulatory regulation on a variety of levels, extending from effects of emotion through effects of peripheral receptors to effects of local metabolites. We are concerned with the regulation of circulation in separate vascular beds (e.g., coronary, skin, muscle, splanchnic), with distribution of blood flow, and with a detailed examination of the microcirculation. We will investigate the response of the circulation to a variety of conditions, including exercise, hemorrhage, and altered behavioral states. Experimental preparations are widely varied, extending from anesthetized animals through intact, unanesthetized animals and humans. We seek to investigate the details of regulation in arterioles and precapillary sphincters (at sites where ultimate control is exerted), and to investigate the details and relative importance of local metabolic control versus autonomic control. We will investigate the existence of "patterns" in the autonomic discharge to various organs and the changes in these autonomic patterns under a variety of stresses. Where possible, we will provide a quantitative description of the phenomena under study. This description extends to understanding the quantitative significance of regional vasomotor activity in the redistribution of blood flow and in the regulation of total peripheral resistance and blood pressure. The ultimate goals of our studies are both broad and narrow. Certain broad questions can be answered now. In certain cases, the state of knowledge with respect to particular organs is such that questions will be more detailed and less general. The individual component projects emphasize the following aspects of peripheral circulatory control: 1. Control of the microcirculation by local and neural mechanisms. 2. Control of the coronary circulation by autonomic and metabolic factors. 3. Control of arterial blood pressure by arterial baroreceptors. 4. Control of the distribution of blood flow in the human. 5. Influence of higher nervous centers and behavioral states on the circulation.